1. Technical Field
The present invention relates to a vehicle suspension system including a shock absorber having a damping force generating apparatus which generates a damping force by controlling the flow of a working fluid generated by a sliding motion of a piston inside the cylinder.
2. Related Art
As a shock absorber used as cushioning for a motor vehicle or a motorcycle, for example, there is known a variable attenuation damper (semi-active damper) including a cylinder in which oil is sealed as the working fluid, a piton slidably fitted into the cylinder, a piston rod connected to the piston and extending to an outside of the cylinder and a damping force generating apparatus which generates a damping force by controlling a flow of oil generated by sliding of the piston inside the cylinder. In such semi-active damper, the damping force is controlled by adjusting flow resistance of the oil at a valve body arranged in a flow path of working fluid by adjusting an opening degree of the valve body by using a solenoid actuator and the like.
It is also known that an active damper using a hydraulic pressure or an air pressure actuator, for example, controls the damping force, a spring constant and the like by Skyhook control and so on based on vertical acceleration and the like detected by a sensor such as an accelerometer (for example, see Japanese Patent Application Laid-open No. 2014-843).
The above active damper can produce thrust by itself, thereby controlling not only damping force components but also spring/reaction force components, that is, enabling various control. However, manufacturing costs of the active damper are high, the mechanism thereof is complicated, and the power consumption therein is high.